Heat exchanger with sintered metal matrix around tubes



F. A. BURNE Feb. 28, 1967 HEAT EXGHANGER WITH SINTERED METAL MATRIXAROUND TUBES Filed Dec. 25. 1964 2 Sheets-Sheet 1 IN VENTOR mam/cm. BU/P/VE v zhy/a pat 6 W A TTOR/V V Feb. 28, 1967 F. A. BURNE HEATEXCHANGER WITH SINTERED METAL MATRIX AROUND TUBES 2 Sheets-Sheet 2 FiledDec.

FIG 16 ZZZ 1 N VEN TOR. FREDER/C/(A. BURN/5 jfl/ M FIG-7 A T TOPNEVUnited States Patent 3,306,353 HEAT EXCHANGER WITH SINTERED METAL MATRIXAROUND TUBES Frederick A. Burne, Hamden, Conn., assignor to OlinMathieson Chemical Corporation, a corporation of Virginia Filed Dec. 23,1964, Ser. No. 420,567

6 Claims. (Cl. 165164) ample, fins or corrugations across which pass themedia between which the heat exchange is to take place. However, it hasbeen found that greatly increased heat transfer surfaces can be achievedby instead employing a body of pervious material, or a porous bodyhaving interconnected voids. Such a body of pervious material presents alarge number of faces for. heat exchange purposes, as well as otheradvantages to be discussed shortly.

By the instant invention there is provided a unique configuration andarrangement of such a pervious body within a heat exchanger which hasbeen tested and found to result in greatly increased heat exchangeproperties. The concept of the instant invention may be employed in heatexchangers of any desired shape, but is particularly adapted to tubularheat exchangers. As known in the art, the use of heat exchangers of atubular configuration is highly advantageous in certain environmentswhere it is desired that the heat exchange take place wholly within theexchanger. The tubular heat exchangers commonly in use in such anenvironment are of the type known in the art as shell and tube, whereina plurality of tubes con veying one heat exchange medium are arrangedwithin a shell through which is circulated another heat exchange medium,with or without the use of bafiles to direct the flow, which issubstantially axial along the tubes.

In the concept of the instant invention there is provided a heatexchanger in which not only the heat exchange area is increased but theflow of one of the media is directed in a path between and around aseries of inner tubes, the medium flow being substantially perpendicularto the axes of the inner tubes. The advantages resulting from such floware achieved by the provision of a pervious body completely encasing theseries of inner tubes. By a particular configuration and arrangement ofthe tubes and the pervious body, to be discussed hereinafter, space isprovided within the heat exchanger to serve as distribution andcollection manifolds for the heat exchange media resulting in thedesired flow. Furthermore, the instant heat exchanger may be madesufliciently compact so that it may be used in in-line installations,for example, within a radiator hose of an automobile cooling system.

As will be understood, various combinations of metals may be utilized informing the heat exchangers according to the intsant invention; andaccordingly the solid portions and the pervious body may be of the samemetal or alloy, or the pervious structure and the solid member may becomprised of different compositions. For example, both the pervious bodyand solid portions may be formed of the same stainless steels, coppers,brass, carbon steels, aluminums or various combinations thereof. As willbe evident, the ultimate use of the resultant structure determines thespecific combination of alloys to be employed.

The production of the pervious body is most flexible; for example, itmay be produced by a process wherein par- 'perature of the particulatematerial.

3,306,353 Patented Feb. 28, 1967 ice ticles, usually spherical, arepoured by gravity into an appropriately shaped confined space andusually vibrated to cause the particles to compact uniformly. As isobvious, the choice of particle size will largely determine the size ofopenings in the resulting pervious body. The body of particles so packedis then treated in accordance with any of the well known metallurgypractices-cg, sintering, welding; brazing or soldering employing anappropriate coatingto produce a metallic bond between the particles.Thus, there is provided a pervious body whose bulk density, or apparentdensity, is but a fraction of the density of the metal or alloy fromwhich the particles are obtained. Furthermore, such process result-s ina metallic bond between the pervious body and solid material around orwithin the body.

While the above described process is preferred in the instant invention,other processes may be employed. For example, it is possible to blendintimately a particulate material with either a combustible substance ora soluble material whose melting point exceeds the sintering tem- Afterthe blend is compacted and treated to achieve a metallic bond, thecombustible substance may be burned away or the soluble material removedby leaching or dissolving with a liquid. A still further method ofproducing the pervious body comprises melting a metal or alloy andcasting it into the interstices of a loose aggregate of a particulatesoluble material whose melting point exceeds that of the metal,preferably having a specific gravity of the molten metal. Uponsolidification of the metal, a component is produced which contains thenetwork of the soluble material interspersed within the solid metalwhich soluble material is thereupon removed by leaching or dissolving,leaving behind it interstices that interconnects and form a perviousnetwork within the resultant metal body. A still further method ofproducing such pervious bodies comprises weaving or knitting metal wireinto a mesh arranged in a plurality of layers. According to thisprocess, a control of porosity is obtained by appropriate choice of wirediameters and openings arranged between adjoining wires as well as thejuxtapositioning of superimposed layers of the woven or knit mesh.

It is to be understood that the concept of this invention need not belimited to the particular configuration indicated above. For example, atube need not be exclusively employed; any desired shape of exchangermay be provided, with the inner tubes and pervious body shapedaccordingly to fit. Furthermore, the tubes may be of any desiredcross-section, any number of heat exchange media may be employed, theexchanger may be used for either heating or cooling, and the directionof flow of the heat exchange media may take a variety of pat-terns.

It is accordingly an object of this invention to provide a heatexchanger which is highly compact and yet capable of high efficiency andlow pressure drop.

It is a further object of this invention to provide such a heatexchanger having a body of pervious material joined therein by ametallic bond.

It is a still further object to provide such a heat exchanger comprisinga tubular member having a plurality of inner tubes bonded in a body ofpervious material.

It is a still further object to provide such a heat exchanger which maybe employed within a radiator hose of an automobile cooling system.

Additional objects and advantages will become apparout to those skilledin the art from a consideration of the 3 changer of FIGURE 1, takenalong the lines II-II thereof,

FIGURE 3 is a longitudinal cross-section of the heat exchanger of FIGURE1, taken along the lines III-III of FIGURE 2,

FIGURE 4 is a diagrammatic view of a heat exchange medium flowing arounda tube of circular cross-section,

FIGURE 5 is a diagrammatic view of a heat exchange medium flowing arounda tube of substantially elliptical cross-section,

FIGURE 6 is a view similar to FIGURE 2, showing a second embodiment ofthe instant heat exchanger, and

FIGURE 7 is a diagrammatic view of the modular concept of the instantinvention.

A first embodiment of heat exchanger according to this invention isshown in FIGURE 1, and is designated generally by 10. A first heatexchange medium, for example the medium to be employed in heating orcooling, is introduced into the heat exchanger 10 at one end thereof, asshown by the arrow 11, and exits from the opposite end thereof in thedirection of the arrow 12. A second heat exchange medium, for examplethe medium to be cooled or heated, enters the heat exchanger 10 throughany suitable fitting in the direction of the arrow 13, is circulatedthrough the heat exchanger, and exits through a suitable fitting in thedirection of the arrow 14. It will be obvious that any desired mediamight be employed in the instant heat exchanger; for example, the mediumintroduced at 11 may be water and that introduced at 13 may be oil.

Referring now to FIGURE 2 of the drawings, it may be seen that heatexchanger 10 comprises an outer tube 15 and a plurality of inner tubes16 and 17. It will be obvious that the tubes 15, 16, 17 may take anydesired configuration. However, the tube 15 is shown as being of acircular cross-section, the tubes 16 of substantially ellipticalcross-section, and the tubes '17 of a circular crosssection, all forreasons to become evident shortly. Surrounding the inner tubes 16 and 17and joined to such tubes by a metallic bond is a body of perviousmaterial 18. The pervious body 18 is formed in such a manner, to bediscussed hereinafter, that there exists at an upper portion of the heatexchanger 10 a void 19, and at the lower portion thereof a void 20.

As can best be seen in FIGURE 3, communicating through the upper portionof heat exchanger 10 is an inlet fitting 21 which communicates with void19, and at a lower portion of the heat exchanger there is located anoutlet fitting 22 which communicates with void 20. Referring still toFIGURE 3, it may be seen that each of the inner tubes 16 and 17 issecured and sealed at its opposite ends within suitable apertures of twoheader plates 23 and 24. Header plates 23 and 24 are in turn secured andsealed to the inner periphery of tube 15.

As shown, the heat exchanger 10 may be used in a radiator hose of anautomobile cooling system, and accordingly there is no need to seal theends of the heat exchanger as shown in FIGURE 3. It will be evident thatportions of a radiator hose may be merely slipped around the oppositeends of the heat exchanger, and secured in any appropriate fashion, asby standard hose couplings. However, the heat exchanger shown need notbe used exclusively Within a hose; by connection of suitable end plates,provision may be made for connection of additional piping means forcirculation of the first medium.

In either case, it will be evident that one of the heat exchange mediamay be circulated longitudinally through the heat exchanger 10. Such acondition is shown in FIGURE 3, wherein the dashed arrows 25 representthe flow of one heat exchange media, for example the water of anautomotive cooling system. The second heat exchange medium, for exampleoil, may be introduced through the inlet fitting 21 and follow the pathof the solid arrows 26. Specifically, the second heat exchange mediumwould enter through inlet fitting 21, flow within the void 19distributing along the length thereof, through the pervious body 18around the tubes 16 and 17, collecting in the void 20, thence outthrough outlet fitting 22 It will be evident that void 19 fonms adistribution manifold for the entering medium, there being lessresistance to flow in such an area than in the 'pervious body. Afterdistribution along the entire length of manifold 19, the flow would thennecessarily be through the pervious body 18 downward, between and aroundthe tubes 16 and 17. Void 22 would consequently serve as a collectionmanlfold, the fluid collecting and exiting through outlet 22. Obviously,suitable fittings may be connected to fittings 21 and 22 for connectionof appropriate piping of the second medium. Thus, it can be seen that inthe instant heat exchanger, the flow of the second heat exchange mediumis substantially perpendicular to the flow of the first heat exchangemedium, in contrast to heat exchangers presently in use wherein the flowpaths of the two media are substantially parallel.

As indicated hereinbefore the inner tubes 16 and 17 may take any desiredconfiguration; however, the configurations shown have been chosen toachieve maxlmum heat exchange results. Specifically, it has been foundthat tubes having a substantially elliptical cross-section yieldadvantages not obtainable by tubes of the conventional circularcross-section. Such a cross-section may be obtained by flattening aconventional tube until the tube assumes a nearly rectangularcross-sectional configuration. A tube having such a configuration isdesirable for a number of reasons. Firstly, such a configurationpresents a large surface area relative to its frontal area. As known inthe art, the application in which the heat exchanger is to be used andthe allowable pressure drop will dictate the flow through the interiorof the tube. This flow will in turn dictate the frontal area of thetube. By forming the tube in the configuration described, an optimumperiphery of tube wall is presented for any given frontal area. Thus,this surface area is considerably increased over conventionalconfigurations, for example a tube of circular cross-section.

Additionally, the substantially elliptical configuration achievesdesirable results regarding the medium flowing interiorly of the tube.In a tube of, for example, circular cross-section, the heat exchangetaking place is inherently greatest in the regions near the periphery ofthe tube. Accordingly, the medium flowing near the center of the tubeperforms little heat exchange, and passes through the tube withoutperforming its intended function. However, in a substantially ellipticaltube, the amount of medium not taking part in the heat exchange ismaterially reduced, since a greater portion of the medium is directlyadjacent the outer wall of the tube.

Furthermore, when the fiow of the second heat exchange medium isperpendicular to the axis of the tubes, a substantially elliptical tubeprovides additional advantages. Referring now to FIGURE 4 of thedrawings, there is shown diagrammatically a tube T of circularcross-section, through which flows a first heat exchange medium A.Flowing perpendicunlar to the axis of tube T is a second heat exchangemedium represented by the arrows B. As shown, the heat exchange medium Bwill pass around the tube T, performing its heat exchange function, andflow downwardly on toward the next tube. However, as the medium B passesaround the tube T, the flow will inherently miss a portion at the lowerend of tube T represented by the distance S. In such an area, little ifany heat exchange may take place. This area can be substantially reducedby forming the tube in a substantially elliptical configuration. Thus,as seen in FIG- URE 5, the tube T has a first heat exchange medium Aflowing therethrough. The second heat exchange medium B flows about thetube T and, due to the reduction in the disturbance of the flow ofmedium B, the area S is substantially smaller than area S of FIGURE 4.Thus, it,

will be evident that a greater amount of heat exchange takes place atthe lower portion of the substantially elliptical tube than with a tubeof circular cross-section. In FIGURES 4 and 5, the pervious body hasbeen deleted for the sake of clarity. The presence of such a body wouldnot materially alter the flow characteristics discussed above.

Again in applications where the flow of the second heat exchange mediumis perpendicular to the axis of the tubes, substantially ellipticaltubes provide a still further advantage. As indicated hereinbefore, thepervious body surrounding the tubes acts as heat exchange fins for thetubes. It is well known in the art that there exists an aptimum findistance, or optimum fin length, beyond which little heat exchange cantake place. Thus, for two tubes of circular cross-section side by side,the distance between corresponding adjacent points of such tubes will ofcourse vary. Thus, if the two closest points of the adjacent tube be theoptimum fin distance, then any fin distance in excess of this distance,as for example that distance between the two furthermost spaced pointsof the adjacent tubes, performs reduced heat exchange. Similarly, if thedistance between the two furthermost spaced points of the adjacent tubebe the optimum fin distance, then the distance between the two mostclosely spaced points would be less than the optimum fin distance.However, for adjacent tubes of substantially elliptical cross-section,the distances between adjacent points of the two tubes is more nearlyconstant, and hence may be more nearly equal to the optimum fin distancethroughout.

The above-noted advantages resulting from the use of tubes of asubstantially elliptical cross-section yield surprising heat exchangeresults. Of course, such a tube is less able to withstand high pressuresexteriorly than is a tube of circular cross-section. However, in theinstant device, it will be recalled that the tubes are joined by ametallic bond within a pervious body. Such a bond holds the walls of thesubstantially elliptical tubes in tension and increases the stability ofsuch tubes in withstanding high pressures.

Referring now again to FIGURE 2 of the drawings, it will be seen thatthe particular arrangement of the inner tubes 16 and 17 provides all ofthe advantages above noted. The substantially elliptical-tubes 16 are soarranged that the distance between corresponding adjacent points of anytwo adjacent elliptical tubes is very close to the optimum fin distance.The flow of the second heat exchange medium, which has been noted to befrom manifold 19 downwardly to manifold 20, is perpendicular to the axisof the tubes 16 and 17. Accordingly, the noted advantages resulting fromthe substantially elliptical c-ona figuration are also obtained.Obviously, for an outer tube of circular cross-section, which is themost usual form, use of substantially elliptical tubes 16 willnecessarily leave some areas of the pervious body 18 which represent awidth greater than the optimum fin distance but a height greater thanthe height of a tube 16. In such an area, tube 17 of a circularcross-section may be employed if so desired, the distance between theperiphery of circular tube 17 and that of the adjacent tube 16 being asnearly possible the optimum fin distance.

Considering now the method by which the instant heat exchanger may beproduced, it will be evident that the pervious body 18 may be formedabout the tubes 16 and 17 in any of the methods indicated hereinbefore.The tubes 16 and 17 may be positioned in the apertures of end plate 23and 24, and the resulting assembly situated in an appropriate mold.Thereafter, the particles of pervious body may be poured into the mold,with provision having been made for leaving voids 19 and 20. Followingany of the metallurgical processes indicated hereinbefore, a metallicbond may be created between the tubes and the particles of the perviousbody, as well as between each of the particles of the pervious body. Theassembly may then be inspected, and the openings of header plates 23 and24 through which the tubes pass may be appropriately sealed if such aseal has not been accomplished by the preliminary joining process. Theheader plates may then be suitably secured within tube 15 andappropriately sealed. Fittings 21 and 22 may be added at any stage ofthe manufacture, and any (further end fittings added as needed.

Alternatively, the tubes may be positioned within the header plates 23and 24, the resulting assembly situated within thetu be 15, andsupported by an appropriate mold. Portions of one of the header platesmay be apertured so that the particles of pervious body may be insertedtherethrough and a channel core may be provided. The resulting assemblymay then be treated in accordance with any of the foregoing methods tosimultaneously create a metallic bond (A) among the particles of thepervious body, (B) between the tubes 16, 17 and the header plates 23 and24, (C) between the pervious body and each of the tubes 16 and 17, (D)between the pervious body 18 and the header plates 23 and 24, and (E)between the header plates 23 and 24 and the inner periphery of tube 15.Following such treatment, the apertures of the header plates throughwhich the particles of pervious material 18 and core were introduced maybe rescaled. As in the first method of manufacture, the fittings 21 and22 might be added at any stage of the procedure, and any further endfittings could be added after the initial treatment.

A second embodiment of heat exchanger according to this invention isdepicted in FIGURE 6, and is designated generally by 110. It will beunderstood that the exterior appearance of the heat exchanger will begenerally similar to that shown in FIGURE 1, and that FIGURE 6 is across-sectional view similar to FIGURE 2. The tubes 116 are analogous tothe tubes 16 of the first embodiment and, while not shown, it will beevident that the tubes 116 are secured Within the outer tube betweenheader plates similar to plates 23 and 24 of the first embodiment, seeFIGURE 3 of the drawings. Similarly, it will be understood that thetubes 116 convey a second heat exchange medium and the outer tube 115conveys the first heat exchange medium, which is introduced through asuitable inlet 121 and exits through a suitable outlet 122. Again,similar to the first embodiment, a pervious body 118 completelysurrounds the tubes 116.

Referring now to the differences between the second embodiment and thefirst, it may be seen in FIGURE 6 that the pervious body 118 of thesecond embodiment is so formed as to be rectangular in cross-section,for reasons to become evident shortly. Pervious body 118 is formed aboutthe tubes 116 in any of the methods indicated hereinbefore so as toachieve a metallic bond between (A) the various particles of thepervious body, and (B) between the pervious body and each of the tubes.Additionally, the rectangular body is formed so as to include twonon-pervious plates and 131 on opposite side faces of the pervious body118. Plates 130 and 131 may be of any desired construction; thin sheetsof metal have been tested and atound to be satisfactory. Plates 130 and131 may be joined to the pervious body 118 in any conventional fashion,as by supporting the plates in a suitable fixture during the process-ingof the pervious body 118. At some portion along the longitudinal lengthof each of the plates 130 and 131 there is formed apertures 132 and.133, respectively.

Thus, the rectangular body 118 with the tubes 116 joined therein, andthe plates 130 and 131 joined thereto, may be fabricated as a modularunit apart from the tube 115. Subsequently, the resulting unit may bepositioned within a tube 115 and secured therein as by joining lowerportions of plates 130 and 131 to the tube wall, as at 134 and 135, aswell as securely sealing the periphery of each of the header plates tothe interior of tube 115.

Following insertion of the module into tube 115, it will be evident thatthe space adjacent the upper face of the pervious body 118 forms amanifold 119, analogous to manifold 19 of the first embodiment, and thespace below the lower face of the pervious body .118 forms a manifold120, analogous to manifold 20 of the first embodiment. Thus, as in thefirst embodiment, the first heat exchange medium entering through inlet121 distributes longitudinally along manifold 119, is forced through thepervious body 118, collecting in the manifold 120, thence exitingthrough outlet 122. Referring momentarily to FIGURE 2 of the drawings, adisadvantage of the heat exchanger there shown is that it is highlydifiicult to achieve a secure seal between pervious body 18 and theinterior of tube in the portion between manifolds 19 and 20. Any spacebetween the pervious body and the Wall becomes a path of leastresistance and the first heat exchange medium will flow through such aspace and hence bypass the intended route through the pervious body.Referring again to FIGURE 6, such bypass is effectively eliminated inthe second embodiment. As noted above, the lower portions of plates 130and 131 along the full length thereof are effectively sealed to the tubewall 115. Were the upper portions of the plates 130 and 131 alsosimilarly secured, the high pressure on the insides of these plateswould force them outward, leaving a space between the plates 130 and 131and the pervious body 118, resulting in the unfavorable bypass indicatedabove. Accordingly, the upper portions of plates 130 and 131 are notsealed to the tube 115; instead, they are apertured as at 132 and 133.Portions of the first heat exchange medium, upon initial introductioninto the tube 115, will fiow through the apertures 132 and 133 into thespaces between plates 130 and 131 and the adjacent portions of tubes115, such spaces being referenced by the characters 136 and 137. Thesespaces form dead areas or pressure equalization chambers to preventseparation of the plates 130 and 131 from pervious body 118. As noted,the first heat exchange medium introduced will flow into the chambers136 and 137; thereafter, this fluid is trapped within such chambers andperforms no heat exchange function. However, the presence of the mediumin each of the chambers 136 and 137 equalizes the pressure on oppositesides of each of the plates 130 and 131, the pressure of the first heatexchange medium flowing through the pervious body 118 beingsubstantially the same as that trapped in the chambers 136 and 137.

The modular construction noted above is further advantageous in thatconstruction of heat exchangers of various sizes is materiallyfacilitated. Thus, any number of heat exchange modules similar to thatdescribed above may be combined for use in tubes large enough toaccommodate, or to require, more of the inner tubes 116. Obviously themodules may be combined in a variety of fashions, that depicted inFIGURE 7 being merely exemplary, where there is shown, on a reducedscale, a larger tube 215. Interiorly of the tube 215 are situated aplurality of modules 216, 217, 218 and 219, depicted diagrammaticallyfor sake of clarity. The modules 216, 217, 218, 219 may be joinedtogether in any suitable fashion, as by welding at the variousjuxtaposed faces as shown at 220. As was the case when employing onlyone module, lower portions of the modular assembly which contact theinner face of tube 215 are suitably joined along their entire length, asat 221 and 222. The functioning of the modular assembly will thus beanalogous to that discussed above with regard to a single module usedalone.

As will be obvious to those skilled in the art, the perpendicular flowof the second heat exchange medium achieved by the instant device,together with the precise positioning of the internal tubes, attains ahigh degree of heat exchange with a minimum of pressure drop. Theprecise flow indicated distributes the second medium over the entirepervious structure in a uniform manner over a greatly increased heatexchange surface. The construction of the pervious body, as Well as ofthe tubes, will be dictated by the contemplated use of the exchangerdependent upon such factors as the thermal conductivity, specific heat,viscosity, and corrosive nature of the fluid, the presence of cloggingsolids in the fluid, and tolerable pressure drop.

It is to be understood that the invention is not limited to theillustrations described and shown herein which are deemed to be merelyillustrative of the best modes of carrying out the invention, and whichare are susceptible of modifications of form, size, arrangement of partsand detail or operation, but rather is intended to encompass all suchmodifications which are within the spirit and scope of the invention asset forth in the appended claims.

What is claimed is:

1. A tubular heat exchanger for circulation of a plurality of heatexchange media, comprising (A) a first tubular member for conveying afirst heat exchange medium,

(B) a plurality of second tubular members for conveying a second heatexchange medium, disposed within said first tubular member, said secondtubular members having a substantially elliptical cross section, saidelliptical cross section having a long dimension, means for directingsaid second heat exchange medium to one inlet end of said second tubularmembers, and means for collecting said second heat exchange medium at anopposite, outlet end of said second tubular members, the longitudinalaxis of said second tubular members being in parallel relationship toeach other and to the longitudinal axis of said first tubular member,the distance spacing adjacent tubes being constant for essentially theentire length of the said long dimension of said elliptical crosssection, whereby the optimum fin distance for the said second tubularmembers is achieved,

(C) a pervious body filling the spaces between adjacent of said secondtubular members, and between said second tubular members and said firsttubular member, said pervious body being between the said inlet andoutlet means of the said second tubular members, and being joined tosaid second tubular members and to said first tubular member by ametallic bond and comprising:

(1) a first void located between said pervious body and said firsttubular member and extending along the full longitudinal length of saidpervious body, means for directing said first heat exchange medium onlyto said first void thereby effecting controlled distribution of saidfirst heat exchange medium through said pervious body in a path betweensaid second tubular members,

(2) a second void located between said pervious body and said firsttubular member and extendind along the full longitudinal length of saidpervious body for controlled collection of said first heat exchangemedium passing through said pervious body,

(3) said pervious body between said first void and second voids thereofbeing of a cross-section matching the cross-section of said firsttubular member,

whereby said first heat exchange medium passes through said firsttubular member and between said plurality of second tubular members in apath perpendicular to the longitudinal axis of said second tubularmembers.

2. A heat exchanger according to claim 1 further characterized in thatall the second tubular members have essentially the same cross section,the heat exchanger also including a plurality of third tubular memberswithin said pervious body, said third tubular members being of acircular cross-section with their longitudinal axes in parallelrelationship to the longitudinal axes of said second tubular members,said third tubular members being disposed in cross sectional areas ofsaid pervious body adjacent said first conduit where said second tubularmembers would not fit.

3. A heat exchanger for circulation of a plurality of heat exchangemedia, comprising (A) a first conduit means for conveying a first heatexchange medium, (B) at least one heat exchange module secured Withinsaid conduit, said module comprising (1) a plurality of tubular conduitmeans for conveying a second heat exchange medium,

(2) a pervious body surrounding said plurality of tubular conduit meansand joined thereto by a metallic bond, said pervious body being of asubstantially rectangular cross-section,

(3) a pair of non-pervious plates on opposed side faces of said perviousbody, said plates being located Within said first conduit, said platesbeing parallel to the direction of flow of said first heat exchangemedium and parallel to the said plurality of tubular conduit means,

(4) aperture means in said non-pervious plates allowing said first heatexchange medium to pass therethrough, whereby the pressure on oppositesides of each of said plates is substantially equalized,

(C) inlet means in said first conduit means adjacent an upper face ofsaid module, (D) outlet means in said first conduit means adjacent alower face of said module, whereby said first heat exchange mediumpasses through said module from an upper face thereof to a lower facethereof, flowing around said tubular conduit means in a directionperpendicular to the longitudinal axes thereof. 4. A heat exchangeraccording to claim 3 including a plurality of said modules joinedtogether in operative relationship.

5. A heat exchange module for insertion in a conduit adapted to convey afirst heat exchange medium, said module comprising (A) a plurality oftubular conduit means for conveying a second heat exchange medium,

(B) a pervious body surrounding said plurality of tubular conduit meansand joined thereto by a metallic bond, said pervious body being of asubstantially rectangular cross-section,

(C) a pair of non-pervious plates on opposing side faces of, and inintimate contact with, said pervious body, said plates surrounding saidtubular conduit means on the two sides of said tubular conduit meanswhich are parallel to the longitudinal axis of said tubular conduitmeans, and

(D) aperture means in each of said non-pervious plates to allow passageof said first heat exchange medium therethrough, whereby the pressure onopposite sides of each of said plates may be substantially equalized.

6. A heat exchange module according to claim 5 wherein said tubularconduit means are each of a substantially elliptical cross-section andthe distances between corresponding adjacent points on the periphery ofadjacent tubes are substantially equal.

References Cited by the Examiner UNITED STATES PATENTS 1,840,510 1/1932Kelley 165-158 2,401,797 6/1946 Rasmussen l65l80 X FOREIGN PATENTS699,151 10/1953 Great Britain.

ROBERT A. OLEARY, Primary Examiner.

MEYER PERLIN, Examiner.

N, R. WILSON, A. W. DAVIS, Assistant Examiners.

5. A HEAT EXCHANGE MODULE FOR INSERTION IN A CONDUIT ADAPTED TO CONVEY AFIRST HEAT EXCHANGE MEDIUM, SAID MODULE COMPRISING (A) A PLURALITY OFTUBULAR CONDUIT MEANS FOR CONVEYING A SECOND HEAT EXCHANGE MEDIUM, (B) APERVIOUS BODY SURROUNDING SAID PLURALITY OF TUBULAR CONDUIT MEANS ANDJOINED THERETO BY A METALLIC BOND, SAID PERVIOUS BODY BEING OF ASUBSTANTIALLY RECTANGULAR CROSS-SECTION, (C) A PAIR OF NON-PERVIOUSPLATES ON OPPOSING SIDE FACES OF, AND IN INTIMATE CONTACT WITH, SAIDPREVIOUS BODY, SAID PLATES SURROUNDING SAID TUBULAR CONDUIT MEANS ON THETWO SIDES OF SAID TUBULAR CONDUIT MEANS WHICH ARE PARALLEL TO THELONGITUDINAL AXIS OF SAID TUBULAR CONDUIT MEANS, AND (D) APERTURE MEANSIN EACH OF SAID NON-PERVIOUS PLATES TO ALLOW PASSAGE OF SAID FIRST HEATEXCHANGE MEDIUM THERETHROUGH, WHEREBY THE PRESSURE ON OPPOSITE SIDES OFEACH OF SAID PLATES MAY BE SUBSTANTIALLY EQUALIZED.